1. Technical Field
The present invention relates to a test apparatus and a driver circuit.
2. Related Art
One known type of test apparatuses of a device under test such as a semiconductor circuit is an apparatus for conducting a functional test and a direct current test of a device under test (for example, see Japanese Patent Application Publication No. 2002-139551). In a functional test, judgment as to whether a device under test is functional normally is performed based on a response signal outputted from the device under test in response to a pattern signal having a predetermined logic pattern. In a direct current test, whether the power consumed by the device under test falls within a predetermined range or not is judged.
A test apparatus performing a functional test or a direct current test of a device under test includes a functional test circuit and a direct current test circuit for each pin connected to the device under test, and switches which one of the functional test circuit and the direct current test circuit is to be connected to the device under test, depending a test to be performed.
For example, Japanese Patent Application Publication No. 2002-139551 provides a relay on a transmission path between a circuit of a test apparatus and a device under test, to switch which of the driver to output a pattern signal and a direct current test device is to be connected to the device under test. U.S. Pat. No. 6,255,839 also discloses a related technology.
Recent years have seen substantial increase in semiconductor circuits adapted to high frequencies. It has become accordingly desirable to produce a test apparatus for testing a semiconductor circuit which can supply a high frequency pattern signal to a device under test. However, if a relay is provided on a transmission path between a circuit of a test apparatus and a device under test to realize both of the functional test and the direct current test as mentioned above, transmission of the high frequency pattern signal would become comparatively difficult.
Provision of both of the functional test circuit and the direct current test circuit for each pin of a test apparatus would also be problematic because it would incur substantial cost increase of the test apparatus as well as from the point of view of efficient use of circuits because the pins have to switch between a functional test circuit and a direct current test circuit. In addition to the above, provision of a relay for switching between the functional test circuit and the direct current test circuit becomes necessary, which adds further costs.